Cloth simulations take too much ram
You might have a scene such as this.

Scene:


(1) A model/mesh of a humanoid with animated walking. 
(2) A cloth plane/mesh that is serving as a cape for the humanoid.


Assumptions:


(A) Let's assume that (1) is a high-res polygon mesh.  
(B) Let's assume that (2) is a high-res polygon mesh.  
(C) Let's assume that (1) is a collision object for (2).


The amount of collisions for (C) is going to be very high, especially since (A) and (B) is true. There are many possible solutions:

Solutions:


(I) Reduce the subdivisions for (1), resulting in low-res humanoid.
(II) Reduce the subdivisions for (2), resulting in low-res cape.
(III) Create a copy of (1) and reduce the subdivisions for only the
copy. Disable the original humanoid mesh as a collision object;
enable the copy of the humanoid (low-res) as a collision object. Now,
the cape will collide/simulate with the low-res humanoid instead of
the high-res humanoid. Finally, make sure to bake/cache/save the
simulation for the cape; now only render the cape &amp; the high-res
humanoid (don't render the low-res humanoid).


You can do (I), (II), or both (I) &amp; (II). However, I think the better solution is (III) where you make a low-res copy to stand in as a collision object.

Feel free to offer any follow-up questions/comments.